共查询到20条相似文献,搜索用时 15 毫秒
1.
Pressure–composition isotherms were measured for the CO2/octadecyl acrylate system at 45.0, 80.0, and 100.0°C and at pressures up to 307 bar. This system exhibited type I phase behavior with a continuous mixture‐critical curve. The solubility of octadecyl acrylate for the CO2/octadecyl acrylate system increased as the temperature increased at a constant pressure. The experimental results for the CO2/octadecyl acrylate system were modeled with the Peng–Robinson equation of state. A good fit of the data was obtained with the Peng–Robinson equation of state with one adjustable parameter for the CO2/octadecyl acrylate system. Experimental cloud‐point data for the poly(octadecyl acrylate)/CO2/octadecyl acrylate system were measured from 36 to 193°C and at pressures up to 2100 bar, and the added octadecyl acrylate concentrations were 11.9, 25.9, 28.0, 35.0, and 40.0 wt %. Poly(octadecyl acrylate) dissolved in pure CO2 up to 250°C and 2100 bar. Also, adding 45.0 wt % octadecyl acrylate to the poly(octadecyl acrylate)/CO2 solution significantly changed the phase behavior. This system changed the pressure–temperature slope of the phase‐behavior curves from an upper critical solution temperature (UCST) region to a lower critical solution temperature region as the octadecyl acrylate concentration increased. Cloud‐point data to 150°C and 750 bar were examined for poly(octadecyl acrylate)/C2H4/octadecyl acrylate mixtures at octadecyl acrylate concentrations of 0.0, 15.0, and 45.0 wt %. The cloud‐point curve of the poly(octadecyl acrylate)/C2H4 system was relatively flat at 730 bar between 41 and 150°C. The cloud‐point curves of 15.0 and 45.0 wt % octadecyl acrylate exhibited positive slopes extending to 35°C and approximately 180 bar. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 372–380, 2002 相似文献
2.
Phase behavior data are presented for poly(methyl methacrylate) (PMMA: Mw= 15,000, 120,000) in supercritical solvent mixtures of carbon dioxide (CO2) and chlorodifluoromethane (HCFC-22). Experimental cloud point curves, which were the phase boundaries between single and
liquid-liquid phases, were measured by using a high-pressure equilibrium apparatus equipped with a variable-volume view cell
at various CO2 compositions up to about 63 wt% (on a polymer-free basis) and at temperatures up to about 100 °C. The cloud point curves
exhibited the characteristics of a lower critical solution temperature phase behavior. As the CO2 content in the solvent mixture increased, the cloud point pressure at a fixed temperature increased significantly. Addition
of CO2 to HCFC-22 caused a lowering of the dissolving power of the mixed solvent due to the decrease of the solvent polarity. The
cloud point pressure increased with increasing the molecular weight of PMMA. 相似文献
3.
Experimental cloud-point data to 260 °C and 2,500 bar are reported to demonstrate the impact of two cosolvents, acetone and
methanol, on the phase behavior of polyethylene, poly(ethylene-co-2.4 mol% acrylic acid) (EAA2.4), poly(ethylene-co-3.9 mol% acrylic acid) (EAA3.9), poly(ethylene-co-6.9 mol% acrylic acid) (EAA6.9), and poly(ethylene-co-9.2 mol% acrylic acid) (EAA9.2) in ethylene. In pressure-temperature (P-T) space, the miscibility of EAA copolymers in ethylene decreases significantly
with temperature and with increasing acrylic acid content of EAA due to self-association of the acrylic acid segments. Acetone
and methanol, both dramatically enlarge the solubility of EAA copolymers due to the hydrogen bonding with acrylic acids in
the EAA. At low concentrations, methanol is a better cosolvent than acetone. However, the impact of methanol diminishes rapidly
with increasing methanol concentration once all the acrylic acids in the EAA are hydrogen bond with methanol molecules. 相似文献
4.
Complexes (H(2)O/CO(2), e-(H(2)O/CO(2)) and h(+)-(H(2)O/CO(2))) in the reaction system of CO(2) photoreduction with H(2)O were researched by B3LYP and MP2 methods along with natural bond orbital (NBO) analysis. Geometries of these complexes were optimized and frequencies analysis performed. H(2)O/CO(2) captured photo-induced electron and hole produced e-(H(2)O/CO(2)) and h(+)-(H(2)O/CO(2)), respectively. The results revealed that CO(2) and H(2)O molecules could be activated by the photo-induced electrons and holes, and each of these complexes possessed two isomers. Due to the effect of photo-induced electrons, the bond length of C=O and H-O were lengthened, while H-O bonds were shortened, influenced by holes. The infrared (IR) adsorption frequencies of these complexes were different from that of CO(2) and H(2)O, which might be attributed to the synergistic effect and which could not be captured experimentally. 相似文献
5.
Hun‐Soo Byun 《应用聚合物科学杂志》2004,94(3):1117-1125
High‐pressure phase behavior was measured for the CO2–cyclohexyl acrylate and CO2–cyclohexyl methacrylate system at 40, 60, 80, 100, and 120°C and pressure up to 206 bar. This system exhibits type I phase behavior with a continuous mixture‐critical curve. The experimental results for the CO2–cyclohexyl acrylate and CO2–cyclohexyl methacrylate system were modeled using the Peng–Robinson equation of state. Experimental cloud‐point data, at a temperature of 250°C and pressure of 2800 bar, were presented for ternary mixtures of poly(cyclohexyl acrylate)–CO2–cyclohexyl acrylate and poly(cyclohexyl methacrylate)–CO2–cyclohexyl methacrylate systems. Cloud‐point pressures of poly(cyclohexyl acrylate)–CO2–cyclohexyl acrylate system were measured in the temperature range of 40 to 180°C and at pressures as high as 2200 bar with cyclohexyl acrylate concentrations of 22.5, 27.4, 33.2, and 39.2 wt %. Results showed that adding 45.6 wt % cyclohexyl acrylate to the poly(cyclohexyl acrylate)–CO2 mixture significantly changes the phase behavior. This system changed the pressure–temperature slope of the phase behavior curves from the upper critical solution temperature (UCST) region to the lower critical solution temperature (LCST) region with increasing cyclohexyl acrylate concentration. Poly(cyclohexyl acrylate) did not dissolve in pure CO2 at a temperature of 250°C and pressure of 2800 bar. Also, the ternary poly(cyclohexyl methacrylate)–CO2–cyclohexyl methacrylate system was measured below 187°C and 2230 bar, and with cosolvent of 27.4–46.7 wt %. Poly(cyclohexyl methacrylate) did not dissolve in pure CO2 at 240°C and 2500 bar. Also, when 53.5 wt % cyclohexyl methacrylate was added to the poly(cyclohexyl methacrylate)–CO2 solution, the cloud‐point curve showed the typical appearance of the LCST boundary. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1117–1125, 2004 相似文献
6.
The oxidation reaction of CO with O2 on the FeOx/Pt/TiO2 catalyst is markedly enhanced by H2 and/or H2O, but no such enhancement occurs on the Pt/TiO2 catalyst. Isotope effects were studied by H2/D2 and H2O/D2O on the FeOx/Pt/TiO2 catalyst, and almost the same magnitude of isotope effect of ca. 1.4 was observed for the enhancement of the CO conversion
by H2/D2 as well as by H2O/D2O at 60 °C. This result suggests that the oxidation of CO with O2 via such intermediates as formate or bicarbonate in the presence of H2O, in which H2O or D2O acts as a molecular catalyst to promote the oxidation of CO as described below.
相似文献
7.
The effect of potassium on the reaction pathways of adsorbed CH2 and C2H5 species on Rh(111) was investigated by means of reflection absorption infrared spectroscopy (RAIRS) and temperature programmed desorption (TDS). Hydrocarbon fragments were produced by thermal and photo-induced dissociation of the corresponding iodo compounds. Potassium adatoms markedly stabilized the adsorbed CH2 and converted it into C2H4, the formation of which was not observed for K-free Rh(111). New routes of the surface reactions of C2H5 have been also opened in the presence of potassium, namely its transformation into butane and butene. 相似文献
8.
Experimental data of high pressure phase behavior between 35 °C and 105 °C and pressures up to 2,200 bar is presented for
poly(d,l-lactic acid)(d,l-PLA) and poly(lactide-co-glycolide)15 (PLGA15), PLGA25, and PLGA50 in supercritical carbon dioxide, trifluoromethane (CHF3), chlorodifluoromethane (CHClF2), dichloromethane (CH2Cl2), and chloroform (CHCl3). d,l-PLA dissolves in carbon dioxide at pressures of 1,250 bar, in CHF3 at pressures of 500 to 750 bar, and in CHClF2 at pressures of 30–145 bar. As glycolic acid (glycolide) is added to the backbone of PLGA, the cloud point pressure increases
by 36 bar/(mol GA) in carbon dioxide, 27 bar/(mol GA) in CHF3, and by only 3.9 bar/(mol GA) in CHClF2. PLGA50 does not dissolve in carbon dioxide at pressures of 2,800 bar, whereas it is readily soluble in CHClF2 at pressures as low as 95 bar at 40 °C. Cloud point behavior of d,l-PLA, PLGA15, and PLGA25 in supercritical carbon dioxide shows the effect of glycolide content between 35 °C and 108 °C. Also, the phase behavior
for poly(lactic acid) — carbon dioxide-CHClF2 mixture shows the changes of pressure-temperature slope, and with CHClF2 concentration of 6 wt%, 19 wt%, 36 wt% and 65 wt%. The cloud-point behavior shows the impact of glycolide content on the
phase behavior of PLA, PLGA15, PLGA25 and PLGA50 in supercritical CHClF2. A comparison was made between the phase behaviors of d,l-PLA and poly(l-lactide)(l-PLA) in supercritical CHF3. The phase behavior of CHF3 as a cosolvent for 5 wt% d,l-PLA-supercritical carbon dioxide system is presented for the effect being added 10 wt% and 29
wt% to CHF3 content. 相似文献
9.
We have studied the rate of methanol formation over Cu(100) and Ni/Cu(100) from various mixtures of CO, CO2 and H2. It is found that the presence of submonolayer quantities of Ni leads to a strong increase in the rate of methanol formation
from mixtures containing all three components whereas Ni does not influence the rate from mixtures of CO2/H2 and CO/H2, respectively. The influence of the partial pressures of CO and CO2 on the rate indicates that the role of CO is strictly promoting. From temperature-programmed desorption spectra it follows
that the surface concentration of Ni depends strongly on the partial pressure of CO. In this way the increase in reactivity
is interpreted as a CO-induced structural promotion introduced by the stronger bonding of CO to Ni as compared to Cu. It is
suggested that this type of promotional behavior will be of general importance in existent catalysts and perhaps even more
relevant in the development of new or improved bimetallic catalysts.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
Pressure swing adsorption experiments were carried out for the separation of equimolar mixtures of carbon dioxide and methane containing small amounts of hydrogen sulfide, utilizing 4A, 5A, and 13X molecular sieves. High-purity methane of zero or nearly zero hydrogen sulfide concentration was produced in the adsorption stage with 13X and 5A sieves, at high product recovery rates; high-purity carbon dioxide was obtained with the same sieves in the desorption stage. Zeolite 4A was found capable of raising considerably the hydrogen sulfide concentration in the accumulated desorption product (vs. the adsorption feed) at high recovery rates too. Adsorption selectivity values derived from the experimental results for all three gas pairs were in line with some theoretical predictions and experimental data of the literature. 相似文献
11.
Yoon-Seok Jang Jeong-Won Kang Hun-Soo Byun 《Journal of Industrial and Engineering Chemistry》2010,16(4):598-601
Experimental cloud-point data up to 433.2 K and 193.0 MPa are reported for binary and ternary mixtures of poly(benzyl methacrylate) [poly(BzMA)] + carbon dioxide + benzyl methacrylate (BzMA) and poly(benzyl acrylate) [Poly(BzA)] + carbon dioxide + benzyl acrylate (BzA) systems. High-pressure cloud-point data are also reported for Poly(BzMA) + carbon dioxide and Poly(BzA) + carbon dioxide in supercritical dimethyl ether (DME). Cloud-point behavior for the Poly(BzMA) + carbon dioxide + BzMA system was measured in changes of the pressure–temperature (p–T) slope, and with BzMA weight fraction of 50.6, 61.0, 67.2 and 95.0 wt.%. The Poly(BzA) + carbon dioxide + 30.4, 40.7 and 49.4 wt.% BzA systems change the (p–T) curve from upper critical solution temperature region (UCST) to lower critical solution temperature (LCST) region as the BzA concentration increases. With 52.3 wt.% BzA to the Poly(BzA) + carbon dioxide solution, the cloud-point curves are taken on the appearance of a typical lower critical solution temperature boundary. Also, the impact by cosolvent (BzMA and BzA) concentrations for the Poly(BzMA) + DME and Poly(BzA) + DME systems is measured at temperature to 453.2 K and pressure range of 24.6–61.3 MPa. 相似文献
12.
FTIR spectra are reported of CO2 and CO2/H2 on a silica-supported caesium-doped copper catalyst. Adsorption of CO2 on a “caesium”/silica surface resulted in the formation of CO2
− and complexed CO species. Exposure of CO2 to a caesium-doped reduced copper catalyst produced not only these species but also two forms of adsorbed carboxylate giving
bands at 1550, 1510, 1365 and 1345 cm−1. Reaction of carboxylate species with hydrogen at 388 K gave formate species on copper and caesium oxide in addition to methoxy
groups associated with caesium oxide. Methoxy species were not detected on undoped copper catalyst suggesting that caesium
may be a promoter for the methanol synthesis reaction. Methanol decomposition on a caesium-doped copper catalyst produced
a small number of formate species on copper and caesium oxide. Methoxy groups on caesium oxide decomposed to CO and H2, and subsequent reaction between CO and adsorbed oxygen resulted in carboxylate formation. Methoxy species located at interfacial
sites appeared to exhibit unusual adsorption properties. 相似文献
13.
Pressure-composition (p, x) isotherms were obtained for the carbon dioxide + 2-(2-ethoxyethoxy)ethyl acrylate [2-(2-EE)EA] system at five temperatures (313.2 K, 333.2 K, 353.2 K, 373.2 K, and 393.2 K) and pressure up to 22.86 MPa. The carbon dioxide + 2-(2-EE)EA system exhibits type-I phase behavior with a continuous mixture critical curve. The experimental results for carbon dioxide + 2-(2-EE)EA mixtures are correlated using the Peng–Robinson equation of state (PR-EOS) using mixing rule including two adjustable parameters. The critical property of 2-(2-EE)EA is estimated with the Joback–Lyderson method.Experimental data up to 485 K and 206.6 MPa are reported for binary and ternary mixtures of poly(2-(2-ethoxyethoxy)ethyl acrylate) [P(2-(2-EE)EA)] + carbon dioxide + 2-(2-EE)EA, P(2-(2-EE)EA) + carbon dioxide + dimethyl ether (DME), P(2-(2-EE)EA) + carbon dioxide + propylene and P(2-(2-EE)EA) + carbon dioxide + 1-butene systems. High-pressure cloud-point data are also reported for P(2-(2-EE)EA) in supercritical carbon dioxide, propane, propylene, butane, 1-butene, and DME at temperature to 474 K and a pressure range of (8.45–206.6) MPa. Cloud-point behavior for the P(2-(2-EE)EA) + carbon dioxide + 2-(2-EE)EA system were measured in changes of the pressure–temperature (p, T) slope and with 2-(2-EE)EA mass fraction of 0.0 wt%, 5.9 wt%, 14.9 wt%, 30.3 wt% and 60.2 wt%. With 0.650 2-(2-EE)EA to the P(2-(2-EE)EA) + carbon dioxide solution, the cloud point curves take on the appearance of a typical lower critical solution temperature boundary. The P(2-(2-EE)EA) + carbon dioxide + (0.0–46.6) wt% DME systems change the (p, T) curve from upper critical solution temperature region to lower critical solution temperature region as the DME mass fraction increases. Also, the impact by propylene and 1-butene mass fraction for the P(2-(2-EE)EA) + carbon dioxide + propylene and 1-butene system is measured at temperatures to 454 K and a pressure range of (75.7 to 119.6) MPa. 相似文献
14.
A copper-zinc-aluminum methanol synthesis catalyst has been prepared using a precipitated hydrotalcite-type precursor that decomposes to a mixture of the corresponding amorphous oxides at a low temperature. TPR studies show that such a mixture is easy to reduce giving a highly dispersed catalyst. When this is mixed with a zeolite, the resulting hybrid catalyst gives C2-C4 hydrocarbons with very high selectivity. This may be useful in obtaining LPG from synthesis gas. 相似文献
15.
Ken -ichi Maruya Kazumi Ito Kazuhito Kushihashi Yoshiho Kishida Kazunari Domen Takaharu Onishi 《Catalysis Letters》1992,14(1):123-126
The CO-H2 reaction over CeO2 catalysts at around 623 K and 67 kPa forms isoprene with about 20% and 70% selectivities in total and C5 hydrocarbons, respectively. The formation of dienes may be due to the low and high activity of CeO2 for alkene and CO hydrogenation, respectively. 相似文献
16.
《分离科学与技术》2012,47(3):428-433
The separation of bulk quantities of H2S from CO2 was investigated through a series of pressure-swing adsorption experiments utilizing 4A, 5A, and 13X molecular sieves. High selectivity of H2S over CO2 was encountered for all sieves, particularly for the 13X and 5A. Practically pure CO2 was produced in the adsorption stage with fresh 5A and 13X sieves, at high product recovery rates. Efficient H2S purification was obtained with fresh 5A and regenerated 4A zeolites. The experimental results were in line with theoretical predictions of the literature. 相似文献
17.
Yousong Liu Guangbin Ji Junyi Wang Xuanqi Liang Zewen Zuo Yi Shi 《Nanoscale research letters》2012,7(1):663
In the current study, monocrystalline silicon nanowire arrays (SiNWs) were prepared through a metal-assisted chemical etching method of silicon wafers in an etching solution composed of HF and H2O2. Photoelectric properties of the monocrystalline SiNWs are improved greatly with the formation of the nanostructure on the silicon wafers. By controlling the hydrogen peroxide concentration in the etching solution, SiNWs with different morphologies and surface characteristics are obtained. A reasonable mechanism of the etching process was proposed. Photocatalytic experiment shows that SiNWs prepared by 20% H2O2 etching solution exhibit the best activity in the decomposition of the target organic pollutant, Rhodamine B (RhB), under Xe arc lamp irradiation for its appropriate Si nanowire density with the effect of Si content and contact area of photocatalyst and RhB optimized. 相似文献
18.
The interaction of CO2 with K-promoted Mo2C/Mo(100) has been studied with high-resolution electron energy loss spectroscopy, work function measurements and temperature-programmed
desorption. Pre-adsorbed potassium dramatically affects the adsorption behavior of CO2 on the Mo2C/Mo(100) surface. It increases the rate of adsorption, the binding energy of CO2 and it induces the dissociation of CO2 through the formation of negatively charged CO2. Potassium adatoms also promote the dissociation of adsorbed CO over Mo2C.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
19.
《Journal of Sulfur Chemistry》2013,34(6):606-612
Melamine reacted with neat sulfuric acid and fuming nitric acid readily to form two new organic solid acids, namely melamine-(H2SO4)3 and melamine-(HNO3)3. Mixture of them acts as a unique powerful system instead of a hazardous H2SO4/HNO3 system for the direct oxidation of thiols. Also, this system can oxidize the sulfides in the presence of a catalytic amount of KBr and few drops of water. This procedure offers advantages such as very low reaction time, simple work-up, excellent yield and matching with some green chemistry protocols. 相似文献
20.
Adsorbed CH2, CH2 and C2H5 moieties were produced on Pd(100) at 90 K by photoinduced dissociation of the corresponding iodo compounds, and their thermal reactions were established.This laboratory is a part of the Center of Catalysis, Surface and Material Science at the University of Szeged. 相似文献